1. Field of the Invention
This invention relates to vapor phase nitration catalysts. More particularly, this invention relates to catalysts comprising the adduct of:
(a) a Group 4b-Group 3b mixed oxide composition represented by the empirical formula: EQU (M.sup.1.sub.a M.sup.2.sub.b O.sub.c).sub.x (NO.sub.2).sub.y PA1 wherein M.sup.1 is at least one element selected from Group 4b of the Periodic Table of the Elements, M.sup.2 is at least one element selected from Group 3b of the Periodic Table of the Elements, a is 1, b is 0 to 20, c is a number taken to satisfy the average valences of M.sup.1 and M.sup.2 in the oxidation states in which they exist in the composition, x is 1, and y is 0 to c, and PA1 (b) a catalytically effective amount of sulfur trioxide. PA1 (a) an alumina-silica-metal oxide combination represented by the formula: EQU (Al.sub.2 O.sub.3).sub.a (SiO.sub.2).sub.b (M.sub.2/n O).sub.c PA1 wherein M is a metal cation selected from the group consisting of the lanthanides or rare earths, Groups 1b, 2b, 5b, 6b 7b and 8 of the Periodic Table of the Elements, and mixtures thereof, and a, b, and c represent weight percent of the Al.sub.2 O.sub.3, SiO.sub.2 and M.sub.2/n O components, respectively, in the alumina-silica-metal oxide combination, with a being 0 to 100, b being 0 to 100, and c being 0 to 50, and n represents an integer from 1 to 7 of the valence of the metal cation, with the proviso that the sum of (a+b) must be greater than 0, and PA1 (b) a catalytically effective amount of sulfur trioxide. PA1 (a) a Group 4b-Group 3b mixed oxide composition represented by the empirical formula: EQU (M.sup.1.sub.a M.sup.2.sub.b O.sub.c).sub.x (NO.sub.2).sub.y PA1 wherein M.sup.1 is at least one element selected from Group 4b of the Periodic Table of the Elements, M.sup.2 is at least one element selected from Group 3b of the Periodic Table of the Elements, a is 1, b is 0 to 20, c is a number taken to satisfy the average valences of M.sup.1 and M.sup.2 in the oxidation states in which they exist in the composition, x is 1, and y is 0 to c, and PA1 (b) a catalytically effective amount of sulfur trioxide. PA1 (a) a Group 4b-Group 3b mixed oxide composition represented by the empirical formula: EQU (M.sup.1.sub.a M.sup.2.sub.b O.sub.c).sub.x (NO.sub.2).sub.y PA1 wherein M.sup.1 is at least one element selected from Group 4b of the Periodic Table of the Elements, M.sup.2 is at least one element selected from Group 3b of the Periodic Table of the Elements, a is 1, b is 0 to 20, c is a number taken to satisfy the average valences of M.sup.1 and M.sup.2 in the oxidation states in which they exist in the composition, x is 1, and y is 0 to c, and PA1 (b) a catalytically effective amount of sulfur trioxide. PA1 (a) greater selectivity to the desired nitroaromatic compounds; PA1 (b) little, if any, by-product formation (to contaminate the desired product); PA1 (c) high material balance between reactants and products; and PA1 (d) mineral thermal decomposition of the nitrating agent.
The catalysts are characterized by exhibiting a para/ortho isomer distribution of at least about 2/1 during the nitration of monosubstituted aromatic compounds having an ortho-para orientation substituent, especially chlorobenzene.
Nitroaromatic compounds find use as solvents, explosives, dyes, perfumes, and analytical reagents, and are important as intermediates in organic synthesis. As an example, nitroaromatic compounds are convertible by reduction into primary amines, which in turn, are valuable intermediates in the synthesis of dyes, pharmaceuticals, photographic developers, antioxidants, and gum inhibitors.